JP6767829B2 - Object mounting member - Google Patents

Description

The present invention relates to an object mounting member such as a ceramic heater used for mounting and heating an object in a semiconductor manufacturing apparatus or the like.

In semiconductor manufacturing equipment such as CVD, in order to place and fix a wafer (object) and heat-treat it, a ceramic heater (member for placing an object) in which a resistance heating element is embedded inside the substrate is used. The ceramic heater has a substrate having a mounting surface on which the wafer is mounted, a heating element arranged inside the substrate for heating to, for example, 500 ° C. or higher, and a wafer fixed and held on the mounting surface as needed. It is equipped with a vacuum suction mechanism, an electrostatic suction mechanism, etc. Of these, the vacuum suction mechanism, for example, is formed in the substrate and draws a ventilation path leading to a plurality of openings provided on the mounting surface to a vacuum to generate a negative pressure between the mounting surface and the wafer. This is a mechanism for adsorbing a wafer by a pressure difference from the atmospheric pressure (see, for example, Patent Document 1).

In the ceramic heater having the vacuum suction mechanism as described above, when the wafer is placed on the mounting surface and held at a high temperature, the wafer temperature near the opening of the mounting surface tends to decrease locally. It is presumed that the cause is that the radiant heat transfer from the heater is smaller than that in the surrounding area due to the existence of the ventilation path. Due to such a local temperature drop in the vicinity of the opening, it is difficult to equalize the heat on the entire mounting surface, and there is a problem that the entire wafer cannot be heated uniformly.

The above problem may occur not only in a ceramic heater having a vacuum suction mechanism but also in a ceramic heater having a ventilation path and an opening for supplying gas from a mounting surface toward the back surface of a wafer (for example, Patent Document 2). .. That is, in Patent Document 2, as a ventilation path, a porous body is filled in a recess provided on the opposite side of the mounting surface of the ceramic substrate, and a pore penetrating between the mounting surface and the bottom surface of the recess is provided. Although the configuration is disclosed, the above problems can occur even in such a configuration.

Japanese Unexamined Patent Publication No. 2006-287213 Japanese Unexamined Patent Publication No. 2013-232641

The present invention has been made in view of the above conventional problems, and an object of the present invention is to localize a mounting surface of an object mounting member having a ventilation path communicating with the outside through an opening. It is an object of the present invention to provide a member for placing an object, which can suppress a temperature drop and achieve thermalization.

The object mounting member of the present invention includes a substrate having a mounting surface on which the object is mounted and a substrate.
A ventilation path provided inside the substrate and communicating with the outside through an opening formed in the above-mentioned mounting surface,
An object mounting member having a heater provided inside the substrate or below the back surface of the substrate on the side opposite to the previously described mounting surface.
In the ventilation path, a breathable member having air permeability at a position facing the object when the object is placed on the previously described mounting surface and at a position on the previously described mounting surface side of the heater. At least a portion of the are arranged,
A plurality of pin-shaped convex portions are formed on the mounting surface of the substrate .

In the object mounting member of the present invention, by arranging at least a part of the breathable member at the above position of the ventilation path, the mounting surface is compared with the case where the breathable member is not present. A local drop in the temperature of the object directly above the formed opening is suppressed. This is because the breathable member reduces the flow velocity of the air around the opening, reduces the endothermic heat transfer, and suppresses the local temperature decrease of the object. Therefore, it is possible to homogenize the entire mounting surface and evenly heat the object. Further, since it is a breathable member, the breathability of the ventilation path is maintained, and it is possible to supply gas to the vacuum exhaust for adsorption of the object or the back surface (mounting surface side) of the object.

Further, in the object mounting member of the present invention, it is preferable that the upper peripheral edge position of the breathable member is arranged at the same height position as the peripheral edge portion of the opening on the above-mentioned mounting surface. In this way, if the peripheral portion of the opening and the breathable member are at the same height position on the mounting surface, that is, flush with each other, particle accumulation does not occur, so that it is possible to prevent the particles from adversely affecting the object. it can.

Further, in the object mounting member of the present invention, a plurality of the ventilation paths can be provided on the substrate, and in this case, the breathable member is preferably arranged in at least a part of the plurality of ventilation paths. In order to further improve the heat soaking property, it is preferable to arrange the breathable member in all the ventilation paths.

Further, in the object mounting member of the present invention, at least one of the breathable members may be provided with a through hole for communicating the ventilation path with the outside. The breathable member can ensure breathability even more reliably by communicating with the outside through the through hole.

Top view of the ceramic heater according to the embodiment of the present invention. FIG. 5 is a cross-sectional view taken along the line AA of the ceramic heater shown in FIG. The perspective view which shows an example of the breathable member which has a through hole. The schematic cross-sectional view which shows the circumference of the ventilation path of the example which used the aggregate of granular material as a breathable member.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

FIG. 1 is a top view of the ceramic heater (object mounting member) 10 according to the embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA of FIG. The ceramic heater 10 shown in FIGS. 1 and 2 has a disc-shaped substrate 12 for sucking and holding the wafer (object) W on the upper surface side (mounting surface side). The upper surface of the substrate 12 is provided with a plurality of pin-shaped convex portions 14 and a substantially annular annular convex portion 16 extending along the outer peripheral edge portion of the substrate 12 so as to surround the plurality of convex portions 14. ing. In FIG. 1, components such as the convex portion 14 and the annular convex portion 16 are deformed for clarification of the configuration, and in addition to the aspect ratio in the cross-sectional view of each component, the ratio of the width or height to the mutual spacing. Etc. are different from the actual ones.

The plurality of convex portions 14 are arranged concentrically around the center of the substrate 12 at regular intervals in the circumferential direction and the radial direction. The plurality of convex portions 14 are regularly arranged in other modes such as a triangular lattice shape and a square lattice shape, and are locally irregular so as to cause a local difference in density in the circumferential direction or the radial direction. May be placed in. The spacing or pitch of the protrusions 14 is designed to be, for example, 20 [mm] or less, preferably 12 [mm] or less, and more preferably 8 [mm] or less. The amount of protrusion of the convex portion 14 from the upper surface of the substrate 12 is designed to be included in the range of, for example, 5 to 500 [μm].

The convex portion 14 has a columnar shape such as a columnar shape and a prismatic shape, a truncated cone shape such as a truncated cone shape and a truncated cone shape, and a columnar shape or a weight base shape having a step so that the cross-sectional area of the upper part is smaller than that of the lower part. Formed into a shape. The diameter of the upper end portion (contact portion with the wafer W) of the convex portion 14 is designed to be 3.0 [mm] or less. The surface roughness Ra of the upper end portion (contact portion with the wafer W) of the convex portion 14 is designed to be included in the range of 0.01 to 2.0 [μm].

The annular convex portion 16 is formed so that the upper end thereof is at the same height as the upper end of the convex portion 14, or may be formed so as to be lower than the upper end of the convex portion 14. The cross-sectional shape of the annular convex portion 16 along the radial direction of the base 12 may be various shapes such as a rectangular shape, a trapezoidal shape, a semicircular shape, and a semi-elliptical shape.

Six through holes 18 are formed in the substrate 12, and the wafer W adsorbed on the mounting surface of the substrate 12 is separated from the mounting surface in the through holes 18 in the vertical direction of the mounting surface at the time of separation. A lift pin (not shown) that can project upward is inserted. The six through holes 18 are arranged so as to have six-fold rotational symmetry with respect to the center of the substrate 12.

A heat generating resistor 13 is provided as a heater inside the substrate 12, and the wafer W is heated by this heater. The heater may be provided below the back surface of the substrate, and the heating means (for example, a lamp or the like) may be arranged at a position away from the back surface of the substrate.

Further, the substrate 12 is formed with six openings 20, and each of the openings 20 communicates with the ventilation path 22 formed in the substrate 12. In other words, the ventilation path 22 communicates with the outside through the opening 20. The six openings 20 are arranged so as to have six-fold rotational symmetry with respect to the center of the substrate 12. Further, the end of the ventilation path 22 on the opposite side of the opening 20 is connected to a vacuum suction device (not shown), and by operating this vacuum suction device, a negative force is formed between the mounting surface and the wafer W. A pressure is generated, and the wafer W is adsorbed and held by the pressure difference from the atmospheric pressure. Further, the wafer W may be connected to a gas supply device instead of the vacuum suction device, and by operating the gas supply device, the wafer W is transferred by heat transfer via the gas supplied between the mounting surface and the wafer W. It is heated.

A breathable member 24 having breathability is arranged in the vicinity of the opening 20 of the ventilation path 22 on the mounting surface side of the heater 13. As described above, by arranging the breathable member 24 in the ventilation path 22, the local decrease in the temperature of the wafer W directly above the opening 20 is suppressed as compared with the case where the breathable member 24 is not provided. .. Further, since the breathable member 24 has breathability, even if it is arranged in the ventilation path 22, it does not affect the vacuum suction of the wafer W.

The upper peripheral edge position of the breathable member 24 is preferably arranged at the same height as the peripheral edge portion of the opening 20 on the mounting surface of the substrate 12. When the peripheral portion of the opening and the breathable member are at the same height position on the mounting surface, that is, flush with each other, particle accumulation does not occur, so that it is possible to prevent the particles from adversely affecting the object.

Further, the breathable member 24 is indirectly heated via the substrate 12 existing around the breathable member 24, and infrared rays are radiated from the end of the heated breathable member 24, so that the breathable member 24 As a result of heating the wafer W placed directly above the wafer W, it is possible to suppress a local temperature drop of the wafer W.

It is preferable to form a protrusion or the like on the inner wall of the ventilation path 22 to lock the breathable member 24 so that the breathable member 24 does not move due to vacuum suction. In addition, as a method of fixing the breathable member 24 to the ventilation path 22, a method of press-fitting the breathable member 24 and a method of adhering the breathable member 24 to the ventilation path 22 using a heat-resistant adhesive are also adopted. can do.

The breathable member 24 is not particularly limited as long as it has breathability, but for example, a member made of a porous body, a member provided with one or a plurality of through holes for communicating the ventilation path 22 with the outside, and the like. An aggregate of granules and the like can be mentioned.

FIG. 3 shows a form in which four through holes are provided as an example of a member provided with one or a plurality of through holes for communicating the ventilation path 22 and the outside. The breathable member 24 shown in FIG. 3 has a cylindrical shape, and four through holes 25 penetrating the longitudinal direction thereof are formed. When the breathable member 24 is inserted in the vicinity of the opening of the ventilation path 22, the ventilation path 22 and the outside can communicate with each other through the four through holes 25, and the ventilation can be ensured.

Examples of the aggregate of granules include an aggregate of semilux beads, and an example thereof is shown in FIG. In the example shown in FIG. 4, a plurality of ceramic beads 26 are filled in the ventilation path 22 near the opening 20. Further, a partition wall 28 having a through hole smaller than the diameter of the ceramic beads 26 is formed in the ventilation path 22 so that the ceramic beads 26 are not sucked during vacuum suction. As described above, even when a plurality of ceramic beads 26 are filled, since there are gaps between the adjacent ceramic beads 26, the air permeability of the ventilation path 22 can be ensured.

As the material of the breathable member 24, it is preferable to use a material having a large emissivity without being deformed in the temperature range used. This is because by using the breathable member 24 as such a material, the local decrease in the temperature of the wafer W due to radiant heat transfer is further suppressed. Examples of the material having a large emissivity include ceramics and graphite, and among them, alumina, silica, oxides containing these, machinable ceramics, silicon carbide and the like are preferably used.

In particular, when the above-mentioned oxide or silicon carbide is used for the breathable member 24, it is more preferable that the breathable member 24 is a porous body, and the porosity of the porous body is 20% or more and 60% or less. Is preferable. As the oxide porous body, a commercially available alumina porous body or a porous body composed of only alumina having a large particle size can be preferably used. Further, as the machinable ceramics, commercially available Macol (manufactured by Ishihara Chemical Co., Ltd.) and Hotvale (manufactured by Ferrotec Ceramics Co., Ltd.) can be preferably used. In addition, alumina-based glass beads and ceramic beads having a diameter of 500 μm or more can also be preferably used for the breathable member 24.

The emissivity of the breathable member 24 is preferably 0.4 or more, more preferably 0.7 or more in the temperature range used. As the emissivity of the breathable member 24 increases, the amount of radiant heat from the breathable member 24 increases, and it is possible to suppress a local temperature drop of the wafer W placed above the opening 20.

The ratio (L / D) of the height (L) of the breathable member to the diameter (D) of the breathable member shall be 0.1 to 10 from the viewpoint of gas permeability and ease of arrangement of the breathable member. Is preferable. If the L / D is smaller than 0.1, the breathable member becomes excessively thin, and it becomes difficult to stably arrange the breathable member in the ventilation path. Further, if the L / D is larger than 10, the gas permeability of the breathable member becomes excessively small, which causes problems in vacuum exhaust and gas supply.

When the substrate is provided with a plurality of ventilation paths, it is preferable that the breathable member is arranged in at least a part of the plurality of ventilation paths, and all of the plurality of ventilation paths are required for sufficient thermalization. It is preferable to arrange a breathable member in.

In the embodiment shown in FIGS. 1 and 2 above, the ventilation path is connected to the vacuum suction device and the ventilation path is evacuated. However, the present invention is not limited to any of the embodiments, and the ventilation path is not limited to any of the embodiments. May be in the form of a gas supply path for supplying gas to the back surface of the wafer. In the case of that form, the passage direction of the gas in the breathable member is opposite to that shown in FIGS. 1 and 2, but the breathable member suppresses the local temperature drop and the wafer can be homogenized. it can.

The ceramic heater of the present embodiment can be manufactured, for example, as follows. A ceramic heater having a vacuum suction mechanism or a gas supply path is manufactured according to a conventional method. The method for producing such a ceramic heater is not particularly limited. At the same time, a breathable member to be arranged near the opening of the ventilation path (vacuum suction path or gas supply path) of the ceramic heater is manufactured. Then, it can be manufactured by inserting a breathable member through the opening of the ventilation path on the mounting surface of the ceramic heater.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[Example 1]
A powder mixture composed of 97% by mass of aluminum nitride powder and 3% by mass of yttrium oxide powder was obtained, filled in a mold, and subjected to uniaxial pressure treatment. As a result, a first layer having a diameter of 350 mm and a thickness of 12 mm was formed.

Next, on the first layer, as a heat generating resistor (heater), a molybdenum mesh (wire diameter 0.1 mm, opening 50 mesh) having a planar shape having a rotationally symmetric shape and a diameter of 300 mm on the outermost circumference is placed. It was placed. Subsequently, the powder mixture formed earlier was filled on the heat generating resistor to a predetermined thickness to form a second layer. Then, hot press firing was performed at a pressure of 10 MPa at a firing temperature of 1800 ° C. and a firing time of 2 hours to obtain a ceramic sintered body (base) having a diameter of 350 mm and a thickness of 25 mm. Then, a through hole having a diameter of 3 mm was formed from the upper surface to the lower surface of the ceramic sintered body so as to have six-fold rotational symmetry with respect to the center, and used as a ventilation path for vacuum suction. Further, a large number of convex portions (height: 0.1 mm, diameter: 1.0 mm) and annular convex portions (diameter: 298 mm: height: 0.1 mm, width: 1) arranged in a scattered pattern by sandblasting. .5 mm) was formed.

Next, a breathable member (cylindrical shape having a diameter of 3 mm and a height of 5 mm) made of a ceramic porous body (porosity 60%) was embedded in the ventilation path formed as described above.

A hole having a diameter of 8 mm was drilled so as to reach from the back surface of the substrate to the heat generating resistor, and a cylindrical nickel metal terminal having a diameter of 8 mm was brazed to the exposed heat generating resistor in silver to form a terminal.

(Evaluation results)
A blackened dummy wafer was placed on the mounting surface of the produced ceramic heater, power was supplied to the terminals to raise the temperature of the ceramic heater, and the temperature of the surface of the dummy wafer was measured with an IR camera. The power supplied to the terminals was the same for 15 minutes from the time when the surface temperature of the dummy wafer reached 500 ° C. After that, the temperature distribution of the dummy wafer was measured.

It was found that the temperature difference between the maximum temperature and the minimum temperature in the region near the opening of the ventilation path was as small as 0.2 ° C., and the soaking property of the ceramic heater was good.

[Example 2]
The ceramic heater was used in the same manner as in Example 1 except that an alumina protective tube (diameter: 3 mm, height: 5 mm) having four pore through holes having a diameter of 0.13 mm was used as the breathable member. It was prepared and evaluated in the same manner as in Example 1.

(Evaluation results)
The temperature difference between the maximum temperature and the minimum temperature in the region near the opening of the ventilation path was as small as 0.4 ° C., and it was found that the heat equalization property of the ceramic heater was good.

[Comparative Example 1]
A ceramic heater was produced in the same manner as in Example 1 except that a breathable member was not used, and evaluated in the same manner as in Example 1.

(Evaluation results)
The temperature difference between the maximum temperature and the minimum temperature in the region near the opening of the ventilation path was as large as 1.4 ° C., and the soaking property of the ceramic heater was insufficient.

10 Ceramic heater 12 Base 13 Heat-generating resistor (heater)
14 Convex part 16 Annular convex part 18 Through hole 20 Opening 22 Ventilation path 24 Breathable member

Claims (4)

A substrate having a mounting surface on which the object is mounted, and
A ventilation path provided inside the substrate and communicating with the outside through an opening formed in the above-mentioned mounting surface,
An object mounting member having a heater provided inside the substrate or below the back surface of the substrate on the side opposite to the previously described mounting surface.
In the ventilation path, a breathable member having air permeability at a position facing the object when the object is placed on the previously described mounting surface and at a position on the previously described mounting surface side of the heater. At least a portion of the are arranged,
An object mounting member characterized in that a plurality of pin-shaped convex portions are formed on the mounting surface of the substrate . In the object mounting member according to claim 1, the upper peripheral edge position of the breathable member is arranged at the same height as the peripheral edge portion of the opening on the above-mentioned mounting surface. Storage member. In the object mounting member according to claim 1 or 2, the substrate is provided with a plurality of the ventilation paths, and the ventilation member is arranged at least a part of the plurality of ventilation paths. A member for placing an object, which is characterized by. The object mounting member according to any one of claims 1 to 3, characterized in that at least one of the breathable members is provided with a through hole for communicating the ventilation path with the outside. A member for placing an object to be used.